Expose API for imported projects checks

src/Build/BuildCheck/API/IBuildCheckRegistrationContext.cs

@@ -16,4 +16,6 @@ public interface IBuildCheckRegistrationContext
     void RegisterEnvironmentVariableReadAction(Action<BuildCheckDataContext<EnvironmentVariableCheckData>> environmentVariableAction);
 
     void RegisterBuildFinishedAction(Action<BuildCheckDataContext<BuildFinishedCheckData>> buildFinishedAction);
+
+    void RegisterProjectImportedAction(Action<BuildCheckDataContext<ProjectImportedCheckData>> projectImportedAction);
 }

src/Build/BuildCheck/Infrastructure/BuildCheckBuildEventHandler.cs

@@ -4,11 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.Build.Experimental.BuildCheck;
 using Microsoft.Build.Experimental.BuildCheck.Acquisition;
-using Microsoft.Build.Experimental.BuildCheck.Utilities;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Shared;
 
@@ -44,6 +40,7 @@ internal BuildCheckBuildEventHandler(
             { typeof(TaskFinishedEventArgs), (BuildEventArgs e) => HandleTaskFinishedEvent((TaskFinishedEventArgs)e) },
             { typeof(TaskParameterEventArgs), (BuildEventArgs e) => HandleTaskParameterEvent((TaskParameterEventArgs)e) },
             { typeof(BuildFinishedEventArgs), (BuildEventArgs e) => HandleBuildFinishedEvent((BuildFinishedEventArgs)e) },
+            { typeof(ProjectImportedEventArgs), (BuildEventArgs e) => HandleProjectImportedEvent((ProjectImportedEventArgs)e) },
         };
 
         // During restore we'll wait only for restore to be done.
@@ -92,6 +89,7 @@ private void HandleProjectEvaluationStartedEvent(ProjectEvaluationStartedEventAr
                 BuildCheckDataSource.EventArgs,
                 checkContext,
                 eventArgs.ProjectFile!);
+
             _buildCheckManager.ProcessProjectEvaluationStarted(
                 checkContext,
                 eventArgs.ProjectFile!);
@@ -141,6 +139,11 @@ private void HandleEnvironmentVariableReadEvent(EnvironmentVariableReadEventArgs
                 _checkContextFactory.CreateCheckContext(GetBuildEventContext(eventArgs)),
                 eventArgs);
 
+    private void HandleProjectImportedEvent(ProjectImportedEventArgs eventArgs)
+        => _buildCheckManager.ProcessProjectImportedEventArgs(
+                _checkContextFactory.CreateCheckContext(GetBuildEventContext(eventArgs)),
+                eventArgs);
+
     private bool IsMetaProjFile(string? projectFile) => projectFile?.EndsWith(".metaproj", StringComparison.OrdinalIgnoreCase) == true;
 
     private readonly BuildCheckTracingData _tracingData = new BuildCheckTracingData();

src/Build/BuildCheck/Infrastructure/BuildCheckCentralContext.cs

@@ -29,10 +29,11 @@ private record CallbackRegistry(
         List<(CheckWrapper, Action<BuildCheckDataContext<PropertyWriteData>>)> PropertyWriteActions,
         List<(CheckWrapper, Action<BuildCheckDataContext<ProjectRequestProcessingDoneData>>)> ProjectRequestProcessingDoneActions,
         List<(CheckWrapper, Action<BuildCheckDataContext<BuildFinishedCheckData>>)> BuildFinishedActions,
-        List<(CheckWrapper, Action<BuildCheckDataContext<EnvironmentVariableCheckData>>)> EnvironmentVariableCheckDataActions)
+        List<(CheckWrapper, Action<BuildCheckDataContext<EnvironmentVariableCheckData>>)> EnvironmentVariableCheckDataActions,
+        List<(CheckWrapper, Action<BuildCheckDataContext<ProjectImportedCheckData>>)> ProjectImportedCheckDataActions)
     {
         public CallbackRegistry()
-            : this([], [], [], [], [], [], [], [])
+            : this([], [], [], [], [], [], [], [], [])
         {
         }
 
@@ -62,6 +63,7 @@ internal void DeregisterCheck(CheckWrapper check)
     internal bool HasPropertyReadActions => _globalCallbacks.PropertyReadActions.Count > 0;
 
     internal bool HasPropertyWriteActions => _globalCallbacks.PropertyWriteActions.Count > 0;
+
     internal bool HasBuildFinishedActions => _globalCallbacks.BuildFinishedActions.Count > 0;
 
     internal void RegisterEnvironmentVariableReadAction(CheckWrapper check, Action<BuildCheckDataContext<EnvironmentVariableCheckData>> environmentVariableAction)
@@ -90,6 +92,9 @@ internal void RegisterProjectRequestProcessingDoneAction(CheckWrapper check, Act
     internal void RegisterBuildFinishedAction(CheckWrapper check, Action<BuildCheckDataContext<BuildFinishedCheckData>> buildFinishedAction)
         => RegisterAction(check, buildFinishedAction, _globalCallbacks.BuildFinishedActions);
 
+    internal void RegisterProjectImportedAction(CheckWrapper check, Action<BuildCheckDataContext<ProjectImportedCheckData>> projectImportedAction)
+        => RegisterAction(check, projectImportedAction, _globalCallbacks.ProjectImportedCheckDataActions);
+
     private void RegisterAction<T>(
         CheckWrapper wrappedCheck,
         Action<BuildCheckDataContext<T>> handler,
@@ -167,10 +172,14 @@ internal void RunProjectProcessingDoneActions(
     internal void RunBuildFinishedActions(
         BuildFinishedCheckData buildFinishedCheckData,
         ICheckContext checkContext,
-        Action<CheckWrapper, ICheckContext, CheckConfigurationEffective[], BuildCheckResult>
-            resultHandler)
-        => RunRegisteredActions(_globalCallbacks.BuildFinishedActions, buildFinishedCheckData,
-            checkContext, resultHandler);
+        Action<CheckWrapper, ICheckContext, CheckConfigurationEffective[], BuildCheckResult> resultHandler)
+        => RunRegisteredActions(_globalCallbacks.BuildFinishedActions, buildFinishedCheckData, checkContext, resultHandler);
+
+    internal void RunProjectImportedActions(
+        ProjectImportedCheckData projectImportedCheckData,
+        ICheckContext checkContext,
+        Action<CheckWrapper, ICheckContext, CheckConfigurationEffective[], BuildCheckResult> resultHandler)
+        => RunRegisteredActions(_globalCallbacks.ProjectImportedCheckDataActions, projectImportedCheckData, checkContext, resultHandler);
 
     private void RunRegisteredActions<T>(
         List<(CheckWrapper, Action<BuildCheckDataContext<T>>)> registeredCallbacks,

src/Build/BuildCheck/Infrastructure/BuildCheckForwardingLogger.cs

@@ -3,13 +3,7 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.Build.BackEnd.Logging;
-using Microsoft.Build.Experimental.BuildCheck.Acquisition;
 using Microsoft.Build.Framework;
-using static Microsoft.Build.Experimental.BuildCheck.Infrastructure.BuildCheckManagerProvider;
 
 namespace Microsoft.Build.Experimental.BuildCheck.Infrastructure;
 
@@ -20,7 +14,7 @@ namespace Microsoft.Build.Experimental.BuildCheck.Infrastructure;
 /// In the future we may need more specific behavior.
 /// </summary>
 /// <remarks>
-/// Ensure that events filtering is in sync with <see cref="BuildCheckConnectorLogger"/>
+/// Ensure that events filtering is in sync with <see cref="BuildCheckConnectorLogger"/>.
 /// </remarks>
 internal class BuildCheckForwardingLogger : IForwardingLogger
 {
@@ -33,10 +27,10 @@ internal class BuildCheckForwardingLogger : IForwardingLogger
     public string? Parameters { get; set; }
 
     /// <summary>
-    /// Set of events to be forwarded to  <see cref="BuildCheckConnectorLogger"/>
+    /// Set of events to be forwarded to  <see cref="BuildCheckConnectorLogger"/>.
     /// </summary>
-    private HashSet<Type> _eventsToForward = new HashSet<Type>
-    {
+    private HashSet<Type> _eventsToForward =
+    [
         typeof(EnvironmentVariableReadEventArgs),
         typeof(BuildSubmissionStartedEventArgs),
         typeof(ProjectEvaluationFinishedEventArgs),
@@ -47,15 +41,13 @@ internal class BuildCheckForwardingLogger : IForwardingLogger
         typeof(BuildCheckAcquisitionEventArgs),
         typeof(TaskStartedEventArgs),
         typeof(TaskFinishedEventArgs),
-        typeof(TaskParameterEventArgs)
-    };
+        typeof(TaskParameterEventArgs),
+        typeof(ProjectImportedEventArgs),
+    ];
 
     public void Initialize(IEventSource eventSource, int nodeCount) => Initialize(eventSource);
 
-    public void Initialize(IEventSource eventSource)
-    {
-        eventSource.AnyEventRaised += EventSource_AnyEventRaised;
-    }
+    public void Initialize(IEventSource eventSource) => eventSource.AnyEventRaised += EventSource_AnyEventRaised;
 
     public void EventSource_AnyEventRaised(object sender, BuildEventArgs buildEvent)
     {
@@ -65,5 +57,7 @@ public void EventSource_AnyEventRaised(object sender, BuildEventArgs buildEvent)
         }
     }
 
-    public void Shutdown() { }
+    public void Shutdown()
+    {
+    }
 }

src/Build/BuildCheck/Infrastructure/BuildCheckManagerProvider.cs

@@ -6,7 +6,6 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Threading;
 using Microsoft.Build.BackEnd;
 using Microsoft.Build.BackEnd.Logging;
 using Microsoft.Build.BuildCheck.Infrastructure;
@@ -59,7 +58,7 @@ public void ShutdownComponent()
     {
         _instance?.Shutdown();
         _instance = null;
-    } 
+    }
 
     internal sealed class BuildCheckManager : IBuildCheckManager, IBuildEngineDataRouter, IResultReporter
     {
@@ -94,7 +93,7 @@ public void SetDataSource(BuildCheckDataSource buildCheckDataSource)
             {
                 _enabledDataSources[(int)buildCheckDataSource] = true;
                 RegisterBuiltInChecks(buildCheckDataSource);
-            } 
+            }
             stopwatch.Stop();
             _tracingReporter.AddSetDataSourceStats(stopwatch.Elapsed);
         }
@@ -344,11 +343,11 @@ public void RemoveThrottledChecks(ICheckContext checkContext)
         private void RemoveCheck(CheckFactoryContext checkToRemove)
         {
             _checkRegistry.Remove(checkToRemove);
-            
+
             if (checkToRemove.MaterializedCheck is not null)
             {
                 _buildCheckCentralContext.DeregisterCheck(checkToRemove.MaterializedCheck);
-				_ruleTelemetryData.AddRange(checkToRemove.MaterializedCheck.GetRuleTelemetryData());
+                _ruleTelemetryData.AddRange(checkToRemove.MaterializedCheck.GetRuleTelemetryData());
                 checkToRemove.MaterializedCheck.Check.Dispose();
             }
         }
@@ -372,6 +371,18 @@ public void ProcessEvaluationFinishedEventArgs(
                 FileClassifier.Shared.RegisterKnownImmutableLocations(getPropertyValue);
             }
 
+            // run it here to avoid the missed imports that can be reported before the checks registration
+            if (_deferredProjectEvalIdToImportedProjects.TryGetValue(checkContext.BuildEventContext.EvaluationId, out HashSet<string>? importedProjects))
+            {
+                if (importedProjects != null && TryGetProjectFullPath(checkContext.BuildEventContext, out string projectPath))
+                {
+                    foreach (string importedProject in importedProjects)
+                    {
+                        _buildEventsProcessor.ProcessProjectImportedEventArgs(checkContext, projectPath, importedProject);
+                    }
+                }
+            }
+
             _buildEventsProcessor
                 .ProcessEvaluationFinishedEventArgs(checkContext, evaluationFinishedEventArgs, propertiesLookup);
         }
@@ -392,6 +403,16 @@ public void ProcessEnvironmentVariableReadEventArgs(ICheckContext checkContext,
             }
         }
 
+        public void ProcessProjectImportedEventArgs(ICheckContext checkContext, ProjectImportedEventArgs projectImportedEventArgs)
+        {
+            if (string.IsNullOrEmpty(projectImportedEventArgs.ImportedProjectFile))
+            {
+                return;
+            }
+
+            PropagateImport(checkContext.BuildEventContext.EvaluationId, projectImportedEventArgs.ProjectFile, projectImportedEventArgs.ImportedProjectFile);
+        }
+
         public void ProcessTaskStartedEventArgs(
             ICheckContext checkContext,
             TaskStartedEventArgs taskStartedEventArgs)
@@ -414,6 +435,7 @@ public void ProcessTaskParameterEventArgs(
                 .ProcessTaskParameterEventArgs(checkContext, taskParameterEventArgs);
 
         private readonly List<BuildCheckRuleTelemetryData> _ruleTelemetryData = [];
+
         public BuildCheckTracingData CreateCheckTracingStats()
         {
             foreach (CheckFactoryContext checkFactoryContext in _checkRegistry)
@@ -445,6 +467,8 @@ public void FinalizeProcessing(LoggingContext loggingContext)
         private readonly ConcurrentDictionary<int, string> _projectsByInstanceId = new();
         private readonly ConcurrentDictionary<int, string> _projectsByEvaluationId = new();
 
+        private readonly Dictionary<int, HashSet<string>> _deferredProjectEvalIdToImportedProjects = new();
+
         /// <summary>
         /// This method fetches the project full path from the context id.
         /// This is needed because the full path is needed for configuration and later for fetching configured checks
@@ -515,6 +539,10 @@ public void ProcessProjectEvaluationStarted(
             string projectFullPath)
         {
             _projectsByEvaluationId[checkContext.BuildEventContext.EvaluationId] = projectFullPath;
+            if (!_deferredProjectEvalIdToImportedProjects.ContainsKey(checkContext.BuildEventContext.EvaluationId))
+            {
+                _deferredProjectEvalIdToImportedProjects.Add(checkContext.BuildEventContext.EvaluationId, [projectFullPath]);
+            }
         }
 
         /*
@@ -523,7 +551,6 @@ public void ProcessProjectEvaluationStarted(
          *
          */
 
-
         public void EndProjectEvaluation(BuildEventContext buildEventContext)
         {
         }
@@ -548,6 +575,24 @@ public void StartProjectRequest(ICheckContext checkContext, string projectFullPa
         }
 
         private readonly Dictionary<int, List<BuildEventArgs>> _deferredEvalDiagnostics = new();
+
+        /// <summary>
+        /// Propagates a newly imported project file to all projects that import the original project file.
+        /// This method ensures that if Project A imports Project B, and Project B now imports Project C,
+        /// then Project A will also show Project C as an import.
+        /// </summary>
+        /// <param name="evaluationId">The evaluation id is associated with the root project path.</param>
+        /// <param name="originalProjectFile">The path of the project file that is importing a new project.</param>
+        /// <param name="newImportedProjectFile">The path of the newly imported project file.</param>
+        private void PropagateImport(int evaluationId, string originalProjectFile, string newImportedProjectFile)
+        {
+            if (_deferredProjectEvalIdToImportedProjects.TryGetValue(evaluationId, out HashSet<string>? importedProjects)
+                && importedProjects.Contains(originalProjectFile))
+            {
+                importedProjects.Add(newImportedProjectFile);
+            }
+        }
+
         void IResultReporter.ReportResult(BuildEventArgs eventArgs, ICheckContext checkContext)
         {
             // If we do not need to decide on promotability/demotability of warnings or we are ready to decide on those

src/Build/BuildCheck/Infrastructure/BuildEventsProcessor.cs

@@ -96,6 +96,16 @@ internal void ProcessEnvironmentVariableReadEventArgs(ICheckContext checkContext
         _buildCheckCentralContext.RunEnvironmentVariableActions(checkData, checkContext, ReportResult);
     }
 
+    /// <summary>
+    /// The method handles events associated with the ProjectImportedEventArgs.
+    /// </summary>
+    internal void ProcessProjectImportedEventArgs(ICheckContext checkContext, string projectPath, string importedProjectPath)
+    {
+        ProjectImportedCheckData checkData = new(importedProjectPath, projectPath, checkContext.BuildEventContext?.ProjectInstanceId);
+
+        _buildCheckCentralContext.RunProjectImportedActions(checkData, checkContext, ReportResult);
+    }
+
     internal void ProcessBuildDone(ICheckContext checkContext)
     {
         if (!_buildCheckCentralContext.HasBuildFinishedActions)

src/Build/BuildCheck/Infrastructure/CheckRegistrationContext.cs

@@ -2,13 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Threading;
-using Microsoft.Build.Experimental.BuildCheck;
 using Microsoft.Build.Experimental.BuildCheck.Checks;
 
 namespace Microsoft.Build.Experimental.BuildCheck.Infrastructure;
 
-internal sealed class CheckRegistrationContext(CheckWrapper checkWrapper, BuildCheckCentralContext buildCheckCentralContext) : IInternalCheckRegistrationContext
+internal sealed class CheckRegistrationContext(CheckWrapper checkWrapper, BuildCheckCentralContext buildCheckCentralContext)
+    : IInternalCheckRegistrationContext
 {
     public void RegisterEnvironmentVariableReadAction(Action<BuildCheckDataContext<EnvironmentVariableCheckData>> environmentVariableAction) =>
         buildCheckCentralContext.RegisterEnvironmentVariableReadAction(checkWrapper, environmentVariableAction);
@@ -33,4 +32,7 @@ public void RegisterProjectRequestProcessingDoneAction(Action<BuildCheckDataCont
 
     public void RegisterBuildFinishedAction(Action<BuildCheckDataContext<BuildFinishedCheckData>> buildFinishedAction)
         => buildCheckCentralContext.RegisterBuildFinishedAction(checkWrapper, buildFinishedAction);
+
+    public void RegisterProjectImportedAction(Action<BuildCheckDataContext<ProjectImportedCheckData>> projectImportedAction) =>
+        buildCheckCentralContext.RegisterProjectImportedAction(checkWrapper, projectImportedAction);
 }